. >> reporter: in the second study, u.s. researchers found preschool-aged children can imitate what they see on tv. >> a lot of children's programming, even though it's childrenning programming, still shows a lot of violence. >> reporter: the american academy of pediatrics suggests children, older than 2, should watch less than two hours of tv a day. and that kids younger than 2, shouldn't watch any tv at all. >> reporter: the walshes have trained their children so they know whatnot to watch. -- >> they all shout at the same time "we're not allowed to watch that ." >> they also limit tv time during the week. >> reporter: and make sure their children spend most of their time outside, staying active. in south bury mills, new york, vinita nair, wjz eyewitness news. >> in addition to anti-social behavior, researchers found that excess television viewing in children, increased the risk of criminal conviction later in life. >>> check in with eyewitness news at 6:00. for these stories and more, coming up, denise is standing by with